The compounds prevent calcium from flooding parts of the brain known as dopamine neurons, which control movement, without causing significant side effects, the researchers said. Calcium can kill dopamine neurons, which causes the movement disorders that are the main symptoms of Parkinson's disease.

The research was published in October in the journal Nature Communications.

The compounds still need to undergo a clinical trial in humans and additional safety testing in animals before they are used by public. But they are very promising, said Dr. James Surmeier, chair of physiology at the Northwestern University Feinberg School of Medicine. He helped to develop the compounds

"Everything looks beautiful right now. We're very excited, very encouraged about the results right now," Surmeier said. "It's incredibly important, but it's still a little early to tell."

Richard B. Silverman, a chemistry professor at Northwestern and inventor of the molecule that became the well-known drug Lyrica, which is used to treat seizures, also helped develop the new compounds.

Parkinson's disease is chronic and progressive, affecting core motor symptoms, and commonly causing tremor and difficulty initiating movement, Surmeier said. Other signs of the illness include slowed movement or a tendency for patients to shuffle their feet.

"There's an enormous need for a drug to slow or stop the progression of the disease," Surmeier said. "We only have Band-Aids. There's no effective means of treating the disease."

Before they die, these dopamine neurons let calcium inside of them, which stresses the neurons and may cause them to die.

"The calcium causes something to overheat and wear out. (Cells) begin to lose energy and die, and become very sensitive to toxins. We thought that, if we could stop the calcium from working, then we might be able to spare cells from dying," Surmeier said.

An earlier, national clinical trial on Parkinson's disease tested the impact of isradipine, a drug usually prescribed for high blood pressure. But isradipine had side effects, including discomfort from ankle swelling.

"We got to this point where we had an idea of how the disease evolves. We had a target, but we couldn't get enough (medicine) into humans without side effects," Surmeier said. "We needed a very specific drug, without cardiovascular side effects."

Surmeier said he and his fellow researchers "found a class of drugs that looked like therapeutics and did what we hoped," namely to selectively target a specific calcium channel, shut it down and prevent calcium from flooding the dopamine neurons.

"We had a discovery, but there was still a lot of work to be done. We have to optimize the design," Surmeier said.

He and his colleagues plan to focus on making sure that the compounds aren't toxic to animals and that they can be delivered in pill form.